Traditional seed planting apparatus generally have a drill adapted to be pinned to a tractor, wherein the drill has a main frame supporting a series of seed planting units located behind a set of rear wheels and extending at a width larger than a distance between the rear wheels. The planting units can generally be elevated in order to reduce the ground width of the apparatus, allowing the performance of a tighter turn. However, with this configuration, the weight of the elevated planting units acts as a lever arm with respect to the rear wheels and produces an upward force on the tractor which reduces traction of the tractor wheels and induces stress concentrations on the main frame.
U.S. Pat. No. 4,450,779, issued May 29, 1984 to Bailey, shows a seed drill having a main reservoir and seed planting equipment located in front of rear wheels. However, the rear wheels are located at outer lateral ends of the seed planting equipment. The drill therefore has a constant and large ground width, which prevents the performance of tight turns and is impractical in a case where the seed drill needs to travel on a public road.
U.S. Pat. No. 4,653,410 issued Mar. 31, 1987 to Typpi, shows a seed planter with small hoppers located in front of rear wheels. The reduced width of this seed planter facilitates public road travel. However, this reduced width as well as small seed hoppers makes it impractical for seed planting in large fields.
U.S. Pat. No. 4,263,858, issued Apr. 28, 1981 to Dreyer, provides a drill distributing both seed and fertilizer in front of rear wheels. However, some fertilizers need to, be disposed in separate furrows from the seeds because these fertilizers will burn the seeds on contact. No provisions are made in this drill to avoid such burning since both seeds and fertilizers are distributed in close proximity. In addition, because gravity is used to distribute the seeds and fertilizers, the reservoirs need to be elevated, which makes it more complicated to fill the reservoirs since they are usually filled from an open top.
It is against this background and the desire to solve the problems of the prior art that the present invention has been developed.